Who's using Dacs

[Rivendell61]

Speakerfritz,

You are correct that DACs have become much better--but not because of increased sampling rates. High sampling rates (up to c. 96kHz max) are useful to get by poor quality filters. The better the filter the lower the rate at which a DAC can operate in a transparent, or near transparent fashion. As noted above any converter being operated above 96kHz will be damaging the signal. So there is a trade off-- Look for better engineering not higher rates.

The McIntosh is a case in point. Contrary to popular 'knowledge' designing a good converter is damned difficult. The difficult part is not buying a chip but designing a board and circuit that can extract the signal. One simple guide to a converter quality is look at the specs. How well did the engineer who designed it do? Most modern chips (Wolfson, AD, etc) have a SNR of c. 117dB+ (and similar dynamic range). So look at the converter specs. The McIntosh says 110+.... Not a good sign. Perhaps on a par with a box from Circuit City :-). And they make no mention of jitter rejection, etc....

Just a note from reading posts above: some are confusing sampling rate with internal operating rate. All (good) modern converters over-sample WAY up into the megahertz range and operate much like a DSD (SACD) converter at maybe 64xFs (often much higher). But that is independent of the sampling rate.

***--always best to keep a chain operating near the delivery rate -- if you have a good converter. Poor converters need higher rates--only your ears can decide. Higher bit depth is needed for some processing, etc but for a simple capture no.

Mark

[WopOnTour]

***--always best to keep a chain operating near the delivery rate -- if you have a good converter. Poor converters need higher rates--only your ears can decide. Higher bit depth is needed for some processing, etc but for a simple capture no

Cool, Thanks, that makes sense.

Gotta love the range of expertise on this forum! []

WOT

[Audio Flynn]

speakerfritz,
By 10 years ago 8x interpolation (oversampling) was the norm. That
resolves to 352.8K samples per second. The norm for DAC resolution was
20 bits or more.
What has improved mostly is the low level distortion characteristics of
the op-amps used as current to Voltage converters and buffers. You
can get a 10 year old DAC, install pin-compatible op-amps from Analog
Devices or Burr-Brown (TI) and have a very competitive DAC that is
inexpensive.
The 192Ks/s upsampling converter in my Philips DVD 963SA is just a tad
smoother than the 8x interpolation/20 bit system in my Sonic Frontiers
"Transdac" in which I have upgraded the op-amps.
The "old" DACs got us 90% of where we are now. They can be very good
additions to a system.
Leo

Agreed

Funny how Phillips and others (Technics
DVD A-10, Panasonic RP-91, Sony 777es, Toshiba SD 9200) decontented
their early robustly designed DVD players that had better than average
CD playback so quickly. Early adopters apreciating the design and
performance do not support profits the way the commodity market does.

[Mallette]

Sort of like saying I'm sending to 100mb (24bit/96khz) per second but you can only recieve and process 10mb per second (16bit/44.1khz).

What? Data rate for 16/44.1 is indeed a little over 10mb/s for stereo. However, 24/96 is around 33mb/s for stereo, nowhere near 100. Even 24/192 is "only" 66mb/s for stereo. Having done one location recording at 24/192X4 channels, I can tell you that poor computer was flat BUSY.

Perhaps I misunderstood?

Dave

[Guest " "]

Mallette

The comparison was a conceptual illustration, but your numbers take the point home.

Another thought is to say if you compare video at 30 frames per second and 60 frames per second, the 60 frames per second one looks less choppy.

I struggle with the notion that 10 year old processors can hold a candle to current ones.

This is why I am homing in on a 24bit/192 or better architecture. The parallel push-pull dac's are the most appealing to me right now. A sampling rate of 768khz is probally something that will carry me thru 5 or 10 years.

But it is really relative to what you have now. Earlier in the thread, I gave some info on a 50 dollar DAC and how it compared to various DAC's I have running thru out the house.

[DrWho]

This is why I am homing in on a 24bit/192 or better architecture. The parallel push-pull dac's are the most appealing to me right now. A sampling rate of 768khz is probally something that will carry me thru 5 or 10 years.

5 or 10 years? Heck, if anything you should be moving more in the direction of 30kHz or double whatever the limit of your hearing is in 5-10 years...

Increasing the bit-rate is good when doing digital signal processing (where you have rounding errors), but 24Bit is already well below the noise floor of analog electronics, let alone that of the room. You won't be able to realize the higher resolution.

The limiting factor right now is the consistency of the fabrication process and the quality of the clock signal. Though even in light of those issues, there are far more bigger concerns in the big picture...

[skeg1967]

Hi,

While we are talking about DAC's can some explain the difference between the external ones and the ones which are in built into my amp. See specs below. Some of these specs are over my head.

Thanks in advance.

Regards Skeg.

Denon AVC-A1SRA

The AVC-A1SRA is a THX Ultra 2 certified Amplifier that features an equal power 7-channel amplifier section, with identical amplifier design on all 7 channels, each capable of 170W rated into 8 Ohms.

1. 24 bit, 96 kHz A/D Converters
24 bit, 192 kHz A/D conversion (Burr-Brown PCM-1804 x 4) on all analog inputs, including External 7.1 inputs
2. Digital Interface Receiver Supporting 24 bit, 192 kHz
Signals
3. Analog Devices Hammerhead SHARC Dual 32-bit Floating Point DSPs

Featuring the latest Analog Devices 32 bit floating point Hammerhead SHARC DSP devices, the AVC-A1SR provides superb resolution and widest dynamic range of Dolby Digital, DTS and PCM audio signals.
4. 24 bit, 192 kHz All-channels Differential-mode D/A
Conversion

16 Burr-Brown PCM-1738E 24-bit, 192-kHz highest resolution DACs, with DSD compatibility - each audio channel operating in differential mode
5. Featuring Lucasfilm Home THX Cinema 4.0, 5.1 and 6.1 ES post-processing on DTS-ES Extended Surround Discrete 6.1 & DTS-ES Extended Surround Matrix 6.1 Decoding

6. DTS Neo:6 Stereo-To-Surround Decoding
This mode utilizes the DTS matrix encoder to reproduce
2-channel analog an PCM recordings through 5.1 or 6.1
channels. (Provided in 2 modes: Music/Cinema)
7. THX Surround EX Decoding
8. Dolby Digital Decoding

9. Dolby Pro LogicIIx decoding

10. DVD-Audio decoding with Adjustable Digital Bass Management, Delay, Channel Levels and Tone Controls, through DENON Digital Link or External Analog Inputs
11. Pure Direct Mode, to Deliver Pure Audio Quality
In Pure Direct mode, power to the video circuitry and the front panel display is turned off, and during analog input, power to the digital circuitry is also automatically turned off. Furthermore, during 2-channel linear PCM input, the D/A converter section is re-configured to 8 DAC dual-differential operation (4 DAC channels for each audio channel) to provide optimum D/A conversion of 2-channel PCM sound sources, such as CD and DVD-Audio with the highest transparency and widest dynamic range.
12. AL 24 Processing
The AVC-A1SRA includes DENON's renowned 24 bit ALPHA processing technology that reproduces digital signals in a waveform with the smoothness of analog signals. This technology thoroughly suppresses annoying quantization distortion and faithfully reproduces the delicate musical details of low-level signals. AL 24 processing works in 2-channel Stereo, Direct, Pure Direct modes.

13. DENON Digital Link for connection to DVD-A11 for DVD Audio/SACD via a shielded twisted pair connection (1.2Gbps maximum transfer rate)
14. Digital-to-Analog Recording
The AVC-A1SR lets you make analog recordings of digital signal sources.

15. TWO sets of 7.1 external wide bandwidth (100 kHz) inputs for multi-channel formats with full Bass Management

16. RS-232C Port
The AVC-A1SRA includes an RS-232C port for connection to external whole-house control systems, from other companies, and provides a software/firmware upgrade pathway.
17. Support for Multi Zone Configurations
Multi-Zone 1 stereo pre-amp outputs with video output;

Multi-Zone 2 outputs, pre-amp outputs or speaker outputs; Remote In/Out Ports ; 12 and 5 volt triggers
18.The RC-871 is a LCD remote control unit that lets you use IR signals to control your A/V amplifier and related gear

Connections:

Audio

Eight Channel Input for External Decoder x2

Eight Analogue Pre Out (including Sub)

13x Analogue Pair Inputs (inc. 1xphono)

5x Analogue Pair Outputs

6x Digital Optical Inputs/2 xOutputs

6x Digital Coaxial Inputs (inc. 1x RF LD Input)

1x

1x Digital Firewire (IEE-1394) Link

Binding Posts for Speakers A and B, Centre and Rear

Video

3x Component Video (inc. 1x Monitor)

8x S-Video In/ 5x S-Video Out (inc. 2x Monitor)

8x Video In/ 6 x S-Video Out (inc. 2x Monitor)

Dimensions: (w xh xd)

434 x216 x486 mm 29.0kg

[Guest " "]

skeg1967

Before I touch on this...keep in mind...in order to use the DAC in the HT reciever...you need to use a coax cable from your source to the HT reciever. If you use an optical connection or if you use an RCA connection...you are actually using the DAC bultin to your soruce.

The spec's for the DAC you posted are as good as your going to get from a specification perspective, but that does not mean that it will be the best sounding.

There are a few different notions about DAC's and various companies perfected an approach to deliver impressive products.

One approach is th power supply used in the DAC. Some folks are selling DAC's that can run off a car battery. These are usally NOS (non oversampling) and tipcally only 16bit DAC's. The sound perfection is achieved by the few number of componets and the absolutely pure DC power supply. Other folks use traditional DAC chips like the one you have posted, but have an external power supply for the external DAC. The external power supply is about the size of the DAC and they stack on top of each other. In the case of the external power supply, some have 6 independent voltage regulators and layers upon layers of DC filtering to achieve the purest level of DC for the DAC circut.

Another approach is getting rid of the operational amplifiers that are used in most DAC circuts and either using DAC circuts that can drive high loads directly (6 volts in the case of the Mcintosh MDA-1000), or they use tube line stage circuts.

Other DAC's use push-pull architecture using multiple DAC chips. Basicaly the signals are inverted and at some point they merry up as one signal again. Once rejoined, noise is cancelled out and dynamic range is increased.

Some architectures use parallel DAC chips. I have a reciever that has 7 24bit/192khz DAC chips, one for each channel.

So basically, you probally have a good DAC architecture in the HT reciever you posted, assuming the noise level in the HT power supply is high end an uneffected by music dynamics. Thats a mouthful when you think about it.

[DrWho]

If you use an optical connection or if you use an RCA connection...you are actually using the DAC bultin to your soruce.

Actually, optical and coax both transmit the exact same digital signal.

[Audio Flynn]

Hi,

While we are talking
about DAC's can some explain the difference between the external ones
and the ones which are in built into my amp. See specs below. Some of
these specs are over my head.

===============================================

For the chip itself nothing. But there are allot of circuits that can induce jitter in a HT component. Standalone DACs are used to avoid all the vibration, EMI, RFI and other bad stuff that comes from transposrts preamp ICs and so forth that makes the music unnatural.

[jcmusic]

Ok guys I got this little DAC (MHDT Labs Renissance II) on loan from another forum member to try out. As I explained to him at first I wasn't impressed, but it did have some qualities that I liked enough to do some research on. As luck would have it I came across some info about the tube used in it, ( 5670) from the 80's. What I read from a few different places including the builder was to try it with a Western Electric 396a tube. This is the tube that the designer recomends, I now know why. WOW WOW WOW!!!!!!!!! what a difference a tube can make, I can hardly belive it, if I weren't hearing it for myself I might not belive it. This little unit has opened up and just flat out gone to another level. The music sounds so much more real to me, the thing just gets it right I don't know what else I can say. Now understand this is in my system and yours may yeild a different result, but for the money (new $400) I don't think you can go wrong. Please do yourself a favor and try to hear one of these with that WE tube in it. I almost forgot thanks a million to JoshN,

Jay

[mark1101]

I've been looking at the Bel Canto Dac 3. I already have enough tubes in my system, and after reading a lot about these things dialed into Bel Canto for the money (around $1,500 used). The reviews and comparisons have always said good things about it. Benchmark, and Lavry are popular too, especially Benchmark.

With a tube pre and tube amp I didn't even look at the tube Dacs. Maybe I should.....I would be replacing my Jolida JD100 which I have been happier with lately since I tried some different tubes in it.

[Guest " "]

"Actually, optical and coax both transmit the exact same digital signal.'

Actually not.

In the optical path, there are additional componets needed to convert the signal to optical...a transmitter and a reciever....these additional componets are a source of jitter.

In the coax path, these componets, and the jitter problem does not exists.

[jcmusic]

So Fritz are you saying that it should or will sound better with the coaxial connection?

Jay

[zuzu]

I have a PS audio Ultralink DAC that I'm not using. It has to be more than 10 years old. Is this any good? What is it worth today?